<template>
  <div>
    <router-link to="/"
                 tag="div"
                 class="header-abs"
                 v-show="showAbs">
      <div class="iconfont header-abs-back">&#xe624;</div>
    </router-link>
    <div class="header-fixed"
         v-show="!showAbs"
         :style="opacityStyle">
      <router-link to="/" tag="b">
        <div class="iconfont header-fixed-back">&#xe624;</div>
      </router-link>
      景点详情
    </div>

  </div>
</template>

<script>
  export default {
    name: 'Header',
    data(){
      return{
        showAbs: true,
        opacityStyle: {
          opacity: 0
        }
      }
    },
    activated(){
      window.addEventListener('scroll',this.handleScroll())
    },
    deactivated(){
      window.removeEventListener('scroll',this.handleScroll());
    },
    methods: {
      handleScroll(){
        const top = document.documentElement.scrollTop;
        if(top > 60 ){
          let opacity = top / 140;
          opacity = opacity >1 ? 1 : opacity
          this.opacityStyle = { opacity }
          this.showAbs = false;
        }else this.showAbs = true
      }
    }
  }
</script>

<style scoped lang="stylus">
  @import "~style/varibles.styl"
  .header-fixed {
    position: fixed
    top: 0
    left: 0
    right 0
    z-index 2
    height: $headerHeight;
    line-height: $headerHeight;
    text-align: center;
    color: #fff;
    background: $bgColor;
    font-size: .32rem;
  }

  .header-fixed-back {
    position: absolute
    top: 0
    left: 0
    width: .64rem;
    text-align: center;
    font-size: .4rem
  }

  .header-abs {
    position absolute
    left .1rem
    top: .1rem
    width .6rem
    height .6rem
    border-radius .4rem
    background rgba(0, 0, 0, .6)
    text-align center
    line-height .6rem
  }

  .header-abs-back {
    color #fff
    font-size .4rem

  }
</style>
